Air depolarized cell



May 20, 1952 P. A. MARsAL x-:T AL

AIR DEPOLARIZED CELL Filed Sept. 30, 1948 :NVNToRs PAUL A MARSAL RUSSELL p. Fox

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` ATTORNEY Patented Mey 2o, 1952 2,597,116

This invention relates to primary velli'L-.o'f th f th'lectrodes' I6, I8 comprises ablock :of car# ardpolarized, type'and .refersjnfloreparticlfila y bn' 'securedto one of the vlegs'22, 24. Preferably to an' improved construction of such' cells. e the legs 22, 24 are embedded in the carbon blocks Airy depolarized cells of. the type employinga and carbon also fills the perforations 26 in the carbonaceous electrode, a zinc electrode 'a`i1 d a legs' `-22 "24. 0 f the support S. The carbonaceous caustic electrolyte have proved t have" highlyelectodsflf I 8 areheld rigidly between 'interdesirable characteristics andhave mety wii'ahpcorie nal o1ders 28 30,32, 34 at the top kand bottomy siderablecommercial vsuccess b'utth'er ldbf lise, of the container' l 0. has been limited becauseof their lrelA lyflarge Anpairof terminals 36, SSeXtendngjthrough size 'an'd weight as compared witli'th so-@called thejtopend of the lcontainer IU is providedon the yolge 201 ofthe support S. These terminals may be `the conyentionalbrass terminals of ordinary .Itis a principalobject o f'thi's'inventibftof dr `y cells Welded or soldered to the yoke20 or videan'improved construction'of aiifdepol"v d m maylqembossedon the yoke 20. I cells' o'f the carbon-zinc-alkali'" syfste'nf'lJ w chi l I h 1 1the vs uppoI'tS servesseveral functions in makes possible theprodct'ion'of'clls'of this pe. the onstruction'of the invention. It serves to which lare far smallerand lighterthanfth i co nectthe carbon blocks I6, I8 togetherjand. ventional air iep'o1`arze `i|. cells-,presently in co olie mechanical protection to them. Further,

" upport S serves as a current-collecting'demarcial use'.' More fspecica1 `1 y it is en -9 theinvention to provid 'e 'a miniaturqaiig d polarized vcell suited for use in suchdevic'es; s, hearing aids. Another objetisthe,provision f carbonblocks I6, I8. nc .electrode 4 0 amalgamated in accordance .36 resins. is folded overland is in contactwithlthe I IZQgQf, flleLAugust 25,1949, by P. SL Brooks'and 3`5"E.,.A.. Schi1ma cher Attached to the. .bottom ,lof the" z inc felectrode v 4 E l,'. for. yexample Joy riyetin'gjis avt' ',50`suitably composed of copper coated steel,

Dijogides' f ablf, composed 'of a therni plastic moldedabout the @elements lnf thbe any gas formed duringdischargeof thecelle Such gas passesfthrough the carbon and out therapere andprovides external electrical connection'- criventional practice, in the form of a nat: sheet preferablypIQVidCdfwith perforations 42 is sides ofthe 'cntainerjl vA pad 48 formed of` s layers O f. lo ro.us material such as, glass' for example ypolyamide or VinylY copolymer,

active surfacespf thefzinc electrode 40. :A pref erre'c l type of pad isdescribed and claimed in Unitedv States patent application Serial 'N..

attached atfi'ts other end. to a` metal, suitably W ste e1,. fp1ate 52 yvhicfh is'fso constructedl as to for'rrr 40 a.eisureforthegcontainer lo. tab 5 o. ,th us r, external electrical' connection to. thVV erebyeaviding air corrosionv .oftli air ,space .filis .leftat the bottom '0L the containerv |q, if1;tpfyvhicnthe iowerpeenons ef .the carbon blocks I6, I8 extend for the purpose of venting;

insidethereofrad,contigsflheret L. ome-e eetureselhjld' Teeprevenirlmingiof ihearbon;

tions 26 are provided in both legs 22, 24. Each 55 with liquid, which would prevent such Venting,

surface of the metal closure plate 52. The Avvax layer 58 internally seals the cell. The bottom edge of the container I is flanged inwardly over and sealed by a thermoplastic cement on the bot- .-1

tom edges of the metal closure plate 52 as shown at 55 in Fig. l thus providing an external seal for the cell. Bosses 60, 612, 64, 65 are provided on the container I0 adjacent to the apertures I2, Id so that when the cell is placed in contact With a flat surface there will be space between the container and such surface, permitting access of air to the apertures I2, I4.

The cell of the invention is quite simple to construct. For example, the electrode support S may be stamped to shape from a thin strip of steel, which preferably has been coated with a conductive carbonaceous paint of the type conventionally used in the duplex electrodes of flat-type dry cells, the intended leg portions being perforated during this stamping operation. The terminals 35, 33 may then conveniently be provided on the yoke 20. The carbon blocks I6, I5 may then be molded about the intended leg portions of the strip, suitably from a mix comprising the electrode material dened in United States Patent 2,010,608 in comminuted form, a resinous binder, and a waterproong agent such as oil, petrolatum or the rubber solution described in United States Patent 2,017,280 or mixtures thereof. The metal support S may then be formed into the U-shape illustrated in Fig. 3, and a thin coating of thermoplastic cement placed on the margins of the leg portions 22, 24. The assembly is now ready for placement in the container I0.

As above stated, the container may be of metal but is preferably of plastic, and in the preferred construction illustrated in the drawing is formed by injection molding. With this type of construction the assembly of the support S, the terminals 33, 33 and the carbon blocks I5, I8 is placed on a suitable supporting form in a split mold. This mold, so designed as to provide in cooperation with theform the apertures I2, Id,

shoulders 28,30, 32, 34 and the grooves 44, 45 desired in the finished container, is then placed about the formand a thermoplastic resin injection molded about the support S. In this operation the resin used to form the container, the thermo-plastic coated margins of the legs 22, 24 of the support S, and the resinous binder used in the formation of the carbon blocks I5, IB are integrally united, the heat applied during the molding operation being suflicient to soften the resinous binder, thus forminga strong, leakproof bond adjacent to the apertures I2, I4 of the nished container I5. This bond is actually stronger than the carbonaceous electrode. By this construction, the carbonaceous electrode I5, I8, the metal support S carrying the terminals 35, 38 and the container I0 constitute a single unit of the cell. Y

Into the container I0 may now be placed the electrolyte 53. The electrolyte preferably used is a solution of sodium hydroxide and zinc oxide in 4 water, in proportions of about 1 part zinc oxide, 31/2 parts sodium hydroxide and l1 parts Water by weight. This solution is preferably immobilized by the incorporation of starch in a proportion of about one-third part by weight in the solution. This electrolyte composition is described and claimed in United States patent application Serial No. 67,758, filed December 28, 1948 by E. A. Schumacher and P. S. Brooks. Sufficient of the electrolyte solution is poured into the container Iii, held top down of course, so that when the' electrode a and pad d8 are inserted, the intervening space between the carbon blocks I5, I8 and the pad 43 is substantially filled with electrolyte solution leaving the air space 54. With the container still held top down the brous pad 133 may be folded over the zinc electrode 40 and the electrode d@ and pad 43 inserted in the container I5, opposite edges of the electrode 45 engaging the grooves 34, Q5 provided in the container i5. The electrode 135 and pad 48 are pushed into the container I5 until the inner surface of the metal closure plate 52 engages the shoulders 32, 34.

After the electrolyte-starch solution has set, the container may be turned top up. The bottom of the container I5 is then locally heated to soften the plastic of which it is composed, and the softened ends inwardly anged over the metal closure plate 52 as shown'at 55 in Fig. 1. By such application of heat, the thermoplastic cement on the closure plate 52 and the wax. layer 53 are softened, the former sealing the plastic of the container iii to the closure plate 52 and the latter forming an internal seal as shown for example in United States Patent 2,244,016. The cell is now complete. Preferably the apertures I2, I4 of the completed cell are covered with a removable Inaterial 59 (Figs. 1 and 2) of lovr moisture-vapor transmission to protect the cell from drying out. This covering is removed before the cell is putto use.

It is of the utmost importance that a cell to be used in devices such as hearing aids carried on the person be of leakproof construction for obvious reasons. The cell of this invention is leakproof by virtue of the sealing into the container of all of the elements of the cell. Leakage of electrolyte through the carbon of the electrodes I6, I8 is prevented by the waterproofing agent incorporated in the carbon. Leakage around the apertures I2, I4 is prevented by the bond formed between the plastic of the container lil, the thermoplastic cement on the metal legs 22, 2d, and the resinous binder in the carbon of the electrodes I6, i8. To secure this bond it is essential that the resin used in the carbon mix, the thermoplastic cement and the container be compatible with each other, although any thermoplastic resin'may be used and different resins may be used for each of these elements of the cell if desired.

yThe cell of the invention Yhas all of the excellent electrical characteristics of conventional air depolarized cells. In contrast to such conventional cells, however, it may be made in very small sizes. A

For instance for use in hearing aids a cellmay be constructed abouttwo inches tall, one inclrwide and one-half inch thick, that is of thev same size as the smallest A batteries now conventionally used in such devices. Its advantages Yover the conventional Le Clanche cells used in hearing aids lie in its far longer life, about threefold,v and its relativelyconstant voltage.

Although a method of constructing` thecell of the invention has been given hereinwin some de. g

y tail; this descriptionfhas been by way'of'xam ple 'merelyl Similarly, although: preferredy mate;

rials tobe used in the'cell have been'rnentioned;

it will beapparent' that other-materials? may be used a'stw'ell. Minor structural-changes'will also occur to those skilled inthe art, asfor example; the replacement ofthe terminals 36;"3'8 with a single terminal, but such rndiiicatio'ns are within' the scope of the invention.

We claimr. Y' y i -1 l; In' an air. depolarized'c'ell aconta'iner having apertures'in opposite walls-forfthe entry of air; a plurality of air-permeable, electrolyte-'repellent carbonaceous electrodes Vspaced apart from each other vand bonded to the interiorwalls 'of" said containerI and covering lthe '-aperturestherein; 'a current-collecting "device" attachedi-tosaid elec#v trode's; "a terminal electrically connected to's'ai'd current-'collecting device/and extending' outward"- l-y of oneend ofv said container; a zinc 'electrode' interposed in said container between said 'car-k bonaceous vielectrodes; an Jimmobilized aqueous electrolyte' in contact with said "carbonaceous electrodes and said zincv electrode'; "and a metal closue'for the other .end ofsaidfcontaner," said closure providing electrical connection` to said Zinc electrode; both ends o'f said container being sealedA against' leakagefand" said carbonaceous electrodes preventing leakage i of liquid' through saidapertures. "1

I 'i 2. In'the combinationfdened'by claim l the improved vconstruction wherein said current-collecting device comprises a strip of metal' embedded i'n said carbonaceous electrodes.

3L In `an airdepolarzed cell a container having apertures on opposite sides thereof for the entry of air; a pair of air-permeable, electrolyte-repellent carbonaceous electrodesspacedv apart from each other and bonded tothe interior walls of said container and covering said apertures; a current-collecting deviceatta'ched to' said electrodes and provided with an electrical 'contact extending outwardly of one-end of `said container; a Vzinc electrode interposed vin` saidcont'aine'r between said vcarbonaceous -"-electrdes; an iin'- mobiliz'ed. aqueous electrolyteii-n lclfnitact witl said carbonaceous electrodes and said `:zinc electrode; anda metal closure for-'the fother end fof said container,` `said closure providingfelectrical connectionto said zinc electrode;said-"container be'- ing-sealed "against leakage at fbeth ends thereof and said carbonaceouselectrodes preventing leakagelof liquid fromsaidapertures. ff 174'. In'an airdepolarizedcell a container having a'pertures in opposite siden wallsfthereof forivthe entry of air; a pair of air-permeable, electrolyterepellent carbonaceous-eleetrodesI 4spaced apart from each other and bonded to the interiorwalls of said container adjacentitosaid apertures, said electrodes coveringY vsaidY apertures `ja metal 'strip attached to both"of saidfcarbon "electrodes";` a terminal electrically connectedt'oAI said strip' and extending outwardly of one end of said container; a zinc electrode interposed between said carbonaceous electrodes in said container; an immobilized aqueous electrolyte in contact with said carbonaceous electrodes and said zinc electrode; and a metal closure on the other end of said container, said closure providing electrical connection to said zinc electrode; said container being sealed against leakage at both ends thereof and said carbonaceous electrodes preventing leakageof liquid through said apertures.

5. In an air depolarized cell a container having apertures in opposite side walls thereof for the 6, entry 'of' a'ir; a pair ofair-permeabIe:electrolyte; repellent 'carbonaceous electrodes "spaced 'apart fr'omfeach other and bonded to the interior walls of said container, said electrodes-covering lsaid apertures; a metal support embedded' in' 'said electrodes connecting the same and-serving as a currentcollecting device'a terminalelectri` cally connected to said metal support:` 'andex-Y tending outwardly.o'fthetop of said container; a 'zinc electrode interposed in'saidxcontainer be-A tween said V-r carbonaceous '-eleetro'des;"an immobilized `'aqueous electolyte'in contact with said carbonaceouselectrodes and said `zinc electrode; and a bottom closure for said container providing electrical connection to said zincpelectrode;` said containerfbeingsealed against leakage at its top and bottom and .said carbonaceous 'electrodes preventing leakage' of liquidI through said 'apere tures: 'v

6.? Inan air depolarized' cell acontainer having apertures ino'pposite sidewalls thereof Ifor the entry ofair'; a pair'of ani-permeable; electrolyte-y repellent Kcarbonaceous` electrodes fsp'aced apart from'each other and bonded tothe interiorwalls of said container,-saidelectrodes covering' said apertures; a' metalfsupport embedded 'said electrodes connecting ithel same Sand serving. as'a current-collecting sdevice; a terminal electrically connected' to 1 sai'd metal slipp'ortand extending outwardly of the .top oflsaidcont'ainer; azing l electrode interposed in'fsaidV container between said carbonaceous electrodes; afiibrous;A electrolyte-permeable. a'lkalf'resistante pad contiguous tothe active surfaces of saidfzinc electrode; an immobilized 'aqueousA electrolyte in contact with said carbonaceousv electrodes; :zinc electrode, and iibrousfpad; Yand a bottomzclosureffor said container providing electrical connectionito said Zinc electrode; said? container being sealed :at -top and bottomv Vagainst leakage andsaidf carbonaceousV electrodes preventing leakage. of :liquidl through: said aperturesw; v l. f f: '7. In anY air depolarized cell acontainer having apertures 4inl oppositeV rside lwalls .thereof for the; entryY of air; apairrof air-permeable, electrolyte-I repellent ;carbonaceous Velectrodes *spaced apart from each other and bonded to the interiorwalls of Vsaid containensaid electrodesfzcoveringsaid apertures; a metal support-having; a.yoke. andfza pair of perforated legs. each of said legsbeing embedded inV one. of'saidfcarbonaceoustelectrodes; a terminal electrically connected to :said-yoke'andl extending outwardly of the topzof saidy container;r a Zinc electrode interposed in said container be-v tween;v said. carbonaceous. electrodes ;i'a fbrous electrolyte-permeable, alkalisresistantpadv .con-` tiguous to .theY active surfacesiof saidfzinc. electrode; an immobilizedelectrolyte in contact with said carbonaceous.. electrodes,11brousfpadzand,

zinc electrode; and Va `v`bottom closurelfor isaid container providing electrical connection.to;saidl zincy electrode; said 'containeriA being; lsealed lat top y and: bottom:againsteleakagey and.. said# car'l bonaceous electrodes preventing leakage of liquid through said apertures.

8. In an air depolarized cell a plastic container having apertures in opposite side walls thereof for the entry of air; a pair of air-permeable, electrolyte repellent carbonaceous electrodes spaced apart from each other and bonded to the interior walls of said container, said electrodes covering said apertures; a metal support having a yoke and a pair of perforated legs, each of said legs being embedded in one of said carbonaceous electrodes and said yoke being embedded in said container; a terminal electrically connected to said yokeand extending outwardly of the top of said container; a zinc electrode interposed in said container between saidcarbonaceous electrodes;

a fibrous, electrolyte-permeable, alkali-resistant pad contiguous to the active surfaces of said zinc electrode; an immobilized electrolyte in contact with said carbonaceous electrodes, fibrous pad and zinc electrode; and a bottom closure for said container providing electrical connection to said zinc electrode; said container being sealed at top and bottom against leakage, and said carbonaceous electrodes preventing leakage of liquid through said apertures.

9. In an air depolarized cell a container having apertures in opposite side Walls for the entry of air; a pair of air-permeable electrolyte-repellent carbonaceous electrodes bonded to the interior walls of said container and covering said apertures; a current-collecting device connected to said carbonaceous electrodes; a terminal electrioally connected to said current-collecting device and extending outwardly of one end of said container; grooves formed in opposite side walls of said container for the reception of a zinc electrode; a at zinc 'electrode mounted in said grooves and having its active surfaces between said carbonaceous electrodes; an immobilized electrolyte in contact with said carbonaceous electrodes and said zinc electrode; and a closure for the other end of said container, said closure providing electrical connection to said zinc.

10. In an air depolarized cell a plastic container having apertures in opposite side walls thereof for the entry of air; a pair of airpermeable, electrolyte-repellent carbonaceous electrodes spaced apart from each other and bonded to the interior walls of said container, said electrodes covering said apertures; a metal support having a yoke and a pair of perforated legs, each of said legs being embedded in one of said carbonaceous electrodes and said yoke being embedded in said container; a terminal electrically connected to said yoke and extending outwardly of the top of said container; grooves formedin opposite .side walls of said container for the reception of a zinc electrode; a flat zinc electrode mounted in said grooves and having its active surfaces between said carbonaceous electrodes a metal tab attached to said zinc electrode and to a metal bottom closure for said cell providing external electrical connection to said zinc electrode; said container being sealed at top and bottom against leakage, and said carbonaceous electrodes preventing leakage of liquid through said apertures.

11. In an air depolarized cell as defined in claim 10 the improvement which comprises a fibrous pad of electrolyte-permeable, alkali-resistant material contiguous to the active surfaces of said zinc electrode.

12. A method of making an air depolarized cell, which method comprises molding a carbonaceous electrode froma mix containing 1comminuted carbon, a resin binder and an electrolyte-repelling agent onto a metal support, placing the'electrode and support in a mold and molding an open-ended, cup-shaped container of a thermoplastic resin compatible with the resin binder of said mix about said electrode and support, thus bonding said electrode and support integrally to the container so formed; inserting in said container a zinc electrode and an electrolyte; closing said container with a metal closure; and

re-molding the open end of said container about v said metal closure.

13. A method of sealing against leakage of liquid an air depolarized cell comprising a container having apertures therein for the entry of air to an air-permeable carbonaceous electrode. which method comprises molding said electrode from a mix comprising comminutedcarbon and a resinous binder; injection molding an openended, cup-shaped container aboutsaid carbonaceous electrode of a thermoplastic resin compatible with said resinous binder; applying suicient heat in said molding operation to soften said resinous binder, thus causing said resinous binder and said thermoplastic resinto unite integrally wherever contact occurs between them; inserting a closure in the open end of the container thus produced; inwardly flanging the open end of said container about the edges of said closure and sealing the so-flanged portions of said container to said closure by a thermoplastic cement.

PAUL A. MARSAL. RUSSELL P. FOX.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 208,614 Lauder Oct. 1, 1873 406,223 Lee l July 2, 1889 1,258,257 Sangers Mar. 5, 1918 1,673,198 Martus et al June 12, 1928 1,856,680 Williams et al May 3, 1932 1,924,314 Heise Aug. 29, 1933 2,050,172 Gordon Aug. 4, 1936 2,154,312 MacCallum Apr. 11, 1939 2,207,734 Heise et al July 16, 1940 2,213,429 Heise et al Sept. 3, 1940 2,307,765 Deibel Jan. 12, 1943 2,409,841 Donkin Oct. 22, 1946 2,422,045 Ruben June 10, 1947 2,450,813 Reinhardt et al. Oct. 5, 1948 FOREIGN PATENTS Number Country Date 11,399 Australia Feb. 17, 1933 224,484 Switzerland Mar. 1, 1943 487,294 Great Britain June 17, 1938 

1. IN AN AIR DEPOLARIZED CELL A CONTAINER HAVING APERTURES IN OPPOSITE WALLS FOR THE ENTRY OF AIR; A PLURALITY OF AIR-PERMEABLE, ELECTROLYTE-REPELLENT CARBONACEOUS ELECTRODES SPACED APART FROM EACH OTHER AND BONDED TO THE INTERIOR WALLS OF SAID CONTAINER AND COVERING THE APERTURES THEREIN; A CURRENT-COLLECTING DEVICE ATTACHED TO SAID ELECTRODES; A TERMINAL ELECTRICALLY CONNECTED TO SAID CURRENT-COLLECTING DEVICE AND EXTENDING OUTWARDLY OF ONE END OF SAID CONTAINER; A ZINC ELECTRODE INTERPOSED IN SAID CONTAINER BETWEEN SAID CARBONACEOUS ELECTRODES; AN IMMOBILIZED AQUEOUS ELECTROLYTE IN CONTACT WITH SAID CARBONACEOUS ELECTRODES AND SAID ZINC ELECTRODE; AND A METAL CLOSURE FOR THE OTHER END OF SAID CONTAINER, SAID CLOSURE PROVIDING ELECTRICAL CONNECTION TO SAID ZINC ELECTRODE; BOTH ENDS OF SAID CONTAINER BEING SEALED AGAINST LEAKAGE, AND SAID CARBONACEOUS 